This invention relates to fuel cells and, in particular, to fuel cells arranged in a fuel cell stack.
In a conventional fuel cell, fuel process gas and oxidant process gas are passed through first and second passages disposed adjacent the anode and cathode electrodes, respectively, to effect electrochemical reaction. The first and second passages are usually arranged in transverse (crossing) fashion in order to situate the entry and exit ports of the passages on different external faces of the cell. This, in turn, permits ready access to the ports through separate external manifolds which provide the necessary isolation between the fuel and oxidant gases. With this type of arrangement, disposition of a plurality of cells in a stack is made easy, since associated cell faces with corresponding ports can be aligned to form a common stack face which can then be served by a common external manifold. A fuel cell stack of this type is disclosed, for example, in U.S. Pat. No. 4,192,906, issued Mar. 11, 1980 and assigned to the same assignee hereof.
It is also customary in fuel cells of the aforementioned type to provide for cooling of the cell. In the `906 patent, this is accomplished by providing third passages for carrying a cooling gas. The entry and exit ports of the third passages are aligned with the entry and exit ports, respectively, of either the first passages or the second passages. In this way, the process gas of the latter passages and the external manifolds serving same also serve as the cooling gas and manifolds, respectively, of the third passages.
While the described arrangement provides desired isolation between oxidant and fuel process gases and desired cooling, research is still being conducted for alternative techniques which, while still providing the necessary isolation, also result in improved fuel cell performance.
It is a primary object of the present invention to provide an improved fuel cell stack.
It is a further object of the present invention to provide a fuel cell stack and associated manifolding which provide enhanced fuel cell stack performance.
It is also an object of the present invention to provide a fuel cell stack and associated manifolding of simple construction.